Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 12/07/19

Area Forecast Discussion

National Weather Service Blacksburg VA

 652 PM EST Fri Dec 6 2019

.SYNOPSIS...
A weak cold front will depart offshore tonight. High pressure
should arrive to provide dry weather for the weekend. Another
cold front will provide a wet start to early next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 140 PM EST Friday...

A weak cold front will cross overhead this afternoon. Skies
should remain cloudy through the evening as light rain showers
linger west of the Blue Ridge. However, the echoes on radar
crossing the Blue Ridge into the Piedmont appear to be mostly
virga. Any shower activity outside of southeast West Virginia
will likely dissipate after sunset. Despite the cloud cover,
the warm air advection from a light southwest breeze is allowing
high temperatures to reach close to model guidance.

After the frontal passage, winds should shift around to the
northwest tonight. A little bit of upslope moisture should
provide a quarter of an inch of snow showers for western
Greenbrier County during the overnight hours. The snow showers
will subside after midnight as drier air arrives. Elsewhere,
skies will partially clear before sunrise as high pressure
begins to build from the northwest. Low temperatures were kept
slightly elevated compared to model guidance due to the clouds
holding for a good chunk of the night. Saturday should be dry
with near seasonable temperatures as high pressure takes control.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 315 PM EST Friday...

A large area of surface high pressure will slide from New England to
off the East Coast.  In concert with the approaching trough to the
west, these features will turn our large scale flow such that it is
southerly.  This will bring increasing amounts of Gulf moisture into
our area on Sunday, building cloud cover throughout the day.

Showers will begin late Sunday night or early Monday morning and
continue with varying strength until Tuesday night, when a strong
cold front passes over the area.  Most of the precipitation
associated with this event will be liquid.

Sunday will be slightly cooler than what is normal for this time of
year, but Monday and Tuesday will see a warm up into the 50s in the
west and even low 60s for parts of the southside.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 315 PM EST Friday...

Rain will continue throughout the day Tuesday, and as the cold
air behind the front approaches on Tuesday night, those west of
the Blue Ridge may see some snow. Overnight into Wednesday
morning some gusty winds will accompany the frontal passage,
especially affecting the higher ridges. Once the front has moved
on, the moist environment of the early week will be supplanted
by drier air and a new surface high heading our way from the
northern plains. The cold air mass behind the front will drop
our temps well below normal for December, so the end of the week
will be chilly.

The next opportunity for active weather will be late Friday or
early Saturday as a low pressure system comes to us from the
south. Guidance has been wavering from run to run on the track
and timing, but there is a good consensus that a surface low
will bring precipitation around next weekend.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 645 PM EST Friday...

A weak front will gradually sink into the region overnight. Do
not expect a lot in the way of weather to accompany the front
and expect locations east of the Blue Ridge to remain VFR
through the period. However, low level moisture will linger west
of the Ridge with a period of MVFR cigs expected at KBCB and
especially at KLWB. KBLF will be up in the clouds and expect IFR
conditions with some fog and drizzle to become established later
tonight. A gradual trend back toward VFR will begin after
daybreak with all sites VFR toward the end of the valid period.

Winds will surge east of the Blue Ridge as the front moves
through with northeast flow becoming a big gusty at KLYH and
KDAN toward daybreak. Otherwise, winds will generally be light
with little impact to aircraft operations.

.Extended Aviation Discussion...

High pressure will keep VFR conditions in place for Saturday
night and Sunday. Confidence continues to increase in poor
flying weather for Monday and Tuesday as a complex low pressure
system develops to provide low ceilings and rain. The cold
front from this low pressure system should cross overhead by
Tuesday night to bring gusty northwest winds for Wednesday.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

$$
SYNOPSIS...PW
NEAR TERM...PW
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...MBS/PW




Area Forecast Discussion

National Weather Service San Diego CA

 205 PM PST Fri Dec 6 2019

.SYNOPSIS...
A moist, southwest flow aloft will bring increasing clouds, with light
rain likely by evening. The clouds will persist through the
weekend, along with a chance for periods of light rain showers as
a weak storm system drops south across the State. It will move
east on Monday, with clearing skies and a warming trend for next
week. Further warming is on tap for next weekend as dry weather
persists. At the beaches, a large west swell bring high surf this
weekend.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

...Update...

Quick update to increase POPS through this evening. Doppler radar
shows a shield of rain entering Orange County extending south off
the San Diego County coast. This area is moving northeast at
about 35 mph. The radar bark is worse than the bite. Aircraft
sounding data shows a dry layer in the lower levels, so some of
the rain falling is evaporating. Upstream gauges over San Clemente
Island show max rain over the past hour of 0.07". So this will be
a light rain but most coast and valley locales do look to get wet
late this afternoon through this evening. As such, increased POPS
substantially to account for this expectation. Rainfall of
trace-0.10 inches is expected through this evening west of the
mountains and along the coastal mountain slopes.

...Previous Discussion (Issued at 1223 PM PST Fri Dec 6 2019)...

Satellite imagery at midday showed a thicker blanket of high clouds
spreading NE across the area. In addition, the radar indicated some
precipitation moving NE over the coastal waters. Some of this could
make it into Orange and San Bernardino Diego Counties by late
afternoon. The sfc pressure gradients from the deserts were still
weak to moderate offshore, supporting NE winds below the passes with
local gusts 25-35 MPH. Still, the sea breeze was evident into the
western valley areas.

A storm system centered 500 miles west of Cape Mendocino today, will
drift east through Saturday, and then drop south through Monday as a
strong ridge builds off the Coast. Weak disturbances off the Pacific
ahead of it will gather up some Pacific moisture, sparking some
occasional light precip that will favor the coastal slopes. Upslope
is generally weak though, so no heavy amounts are likely with no
good atmospheric lift to squeeze it out. Snow levels will be quite
high initially, above 8K FT through Saturday, then fall to around 7K
FT by late Sunday.

The final trough axis passes through SoCal on Monday morning, so
some light, scattered showers may continue into early Monday for San
Diego County especially. Overall precip amounts of 1/4-1/2 inch are
expected west of the mts, and 0.5 to 1.5 inches on the coastal
slopes and higher terrain. For the deserts, less than one-quarter
inch total. Several inches of snow are possible in the San
Bernardino Mts by Mon morning above 7500 FT.

A highly amplified ridge develops early next week along the West
Coast and keeps SoCal protected from activity in the westerlies
through next week. Even though the ridge flattens, it strengthens
further next weekend along 30N latitude. This will likley bring well
above average temps to SoCal by next weekend, along with continued
fair and dry weather.

&&

.AVIATION...
062020Z...Coasts/Valleys...SCT-BKN high clouds AOA 20000 ft MSL and
unrestricted vis this afternoon. Cigs 2000-2500 ft MSL and vis 2-4
SM in areas of RA after 01Z Sat.

Mountains...SCT-BKN high clouds AOA 20000 feet MSL with unrestricted
vis through this afternoon. Low clouds will obscure terrain above
3000 ft MSL, with vis 1-3 SM at times after 01Z Sat with -RA/-SN.

Deserts...Mostly clear skies through Fri. Chance of -RA Sat. Cigs
around 5000 ft MSL and vis 3-5SM possible in RA.

&&

.MARINE...
Scattered rain showers this afternoon through Sunday. Combined seas
of 6 to 8 ft are expected Saturday afternoon through Sunday evening.

&&

.BEACHES...
A High Surf Advisory has been issued as long-period northwest swells
of 14 to 18 seconds arrive at the coasts of Southern California. The
swells will start to build on Saturday, peaking Sunday morning, and
subsiding by Monday morning. Surf of 6-8 ft is expected in San Diego
County and 4-7 ft surf is expected on beaches prone to WNW swells in
Orange County.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory from 4 AM Saturday to 4 AM PST Monday for
     Orange County Coastal Areas-San Diego County Coastal Areas.

PZ...NONE.
&&

$$

PUBLIC...Gregoria (Update)/10 (Prev Discussion)
AVIATION/MARINE...PG